Yemen president's chief of staff abducted in Sanaa
Ahmed Awad bin Mubarak and two of his guards were kidnapped early on Saturday in the centre of the capital Sanaa.
Yemeni officials suspect Shia Houthi rebels, who control much of the capital, of being behind the abduction.
The country has been plagued by instability since mass protests forced former president, Ali Abdullah Saleh, to step down in 2011.
Scores of people have been killed in clashes between the Houthis and Sunni militants.
One source told Reuters Mr Bin Mubarak was kidnapped by the Houthis to stop him presenting a draft of the new constitution to a presidential meeting.The new constitution would see Yemen divided into federally-administered regions, but has been resisted by the Houthis and southern separatists.
Houthi rebels blocked Mr Bin Mubarak's appointment as prime minister last year.
Their critics say they are a proxy for Iran, a charge the rebels deny.
A video purportedly from al-Qaeda in Yemen (AQAP) said it planned and financed the attack on the Charlie Hebdo offices in France that killed 12, but did not provide evidence to support its claims.